Technical Field
The present invention relates to a reclining device coupling a seatback to a seat cushion such that the seatback can adjust an angle relative to the seat cushion, and a vehicle seat including the reclining mechanism.
Related Art
In a reclining device described in Japanese Patent Application Laid-Open (JP-A) No. 2007-130307, a reclining unit (recliner) is provided between a lower arm (lower frame member) at a seat cushion side, and an upper arm (upper frame member) at a seatback side. The recliner is fixed by welding to the lower frame member and the upper frame member.
In reclining devices such as that described above, an excessive load acts on the lower frame member at the seat cushion side from the upper frame member at the seatback side, through the recliner during a collision of the vehicle or the like. When this occurs, force in a detachment direction is applied to weld portions between the recliner and the upper frame member, and between the recliner and the lower frame member, therefore the strength of the weld portions needs to be secured. However, there is also a demand for weight reduction in vehicle seats, and the recliner needs to be smaller in diameter (smaller in size) and the respective frame members need to be thinner, which is counterproductive to securing the strength of the weld portions.